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DatoValore
TitleCOLONIZATION OF OVERLAYING WATER BY BACTERIA FROM DRY RIVER SEDIMENTS
AbstractWe studied the diversity, community composition and activity of the primary microbial colonizers of the water above freshly re-wetted sediments from a temporary river. Dried sediments, collected from Mulargia River (Sardinia, Italy), were covered with sterile freshwater in triplicate microcosms, and changes of the planktonic microbial assemblage were monitored over a 48 h period. During the first 9 h bacterial abundance was low (1.5 ¥ 104 cells ml-1); it increased to 3.4 ¥ 106 cells ml-1 after 28 h and did not change thereafter. Approximately 20% of bacteria exhibited DNA de novo synthesis already after 9 h of incubation. Changes of the ratios of 3H-leucine to 3H-thymidine incorporation rates indicated a shift of growth patterns during the experiment. Extracellular enzyme activity showed a maximum at 48 h with aminopeptidase activity (430.8 22.6 nmol MCA l-1 h-1) significantly higher than alkaline phosphatase (98.6 4.3 nmol MUF l-1 h-1). The primary microbial colonizers of the overlaying water - as determined by 16S rRNA gene sequence analysis - were related to at least six different phylogenetic lineages of Bacilli and to Alphaproteobacteria (Brevundimonas spp. and Caulobacter spp.). Large bacterial cells affiliated to one clade of Bacillus sp. were rare in the dried sediments, but constituted the majority of the planktonic microbial assemblage and of cells with detectable DNA-synthesis until 28 h after re-wetting. Their community contribution decreased in parallel with a rise of flagellated and ciliated protists. Estimates based on cell production rates suggested that the rapidlyenriched Bacillus sp. suffered disproportionally high loss rates from selective predation, thus favouring the establishment of a more heterogenic assemblage of microbes (consisting of Proteobacteria, Actinobacteria and Cytophaga-Flavobacteria). Our results suggest that the primary microbial colonizers of the water above dried sediments are passively released into the plankton and that their high growth potential is counteracted by the activity of bacterivorous protists.
SourceEnvironmental microbiology (Print) 10 (10), pp. 2760–2772
KeywordsBacteriasedimenttemporary riversdroughtstream ecology
JournalEnvironmental microbiology (Print)
EditorBlackwell Science., Oxford, Regno Unito
Year2008
TypeArticolo in rivista
DOI10.1111/j.1462-2920.2008.01695.x
AuthorsFAZI S. (1); AMALFITANO S. (1); PICCINI P. (2); ZOPPINI A. (1); PUDDU A. (1); PERNTHALER J. (3)
Text42269 2008 10.1111/j.1462 2920.2008.01695.x ISI Web of Science WOS 000259147900025 Scopus 2 s2.0 51649106623 Bacteria sediment temporary rivers drought stream ecology COLONIZATION OF OVERLAYING WATER BY BACTERIA FROM DRY RIVER SEDIMENTS FAZI S. 1 ; AMALFITANO S. 1 ; PICCINI P. 2 ; ZOPPINI A. 1 ; PUDDU A. 1 ; PERNTHALER J. 3 1 Water Research Institute IRSA CNR , Roma, Italy; 2 Laboratory of Microbiology, Instituto de Investigaciones Biologicas Clemente Estable, Montevideo, Uruguay; 3 Limnological Station, University of Zurich, Kilchberg, Switzerland. We studied the diversity, community composition and activity of the primary microbial colonizers of the water above freshly re wetted sediments from a temporary river. Dried sediments, collected from Mulargia River Sardinia, Italy , were covered with sterile freshwater in triplicate microcosms, and changes of the planktonic microbial assemblage were monitored over a 48 h period. During the first 9 h bacterial abundance was low 1.5 ¥ 104 cells ml 1 ; it increased to 3.4 ¥ 106 cells ml 1 after 28 h and did not change thereafter. Approximately 20% of bacteria exhibited DNA de novo synthesis already after 9 h of incubation. Changes of the ratios of 3H leucine to 3H thymidine incorporation rates indicated a shift of growth patterns during the experiment. Extracellular enzyme activity showed a maximum at 48 h with aminopeptidase activity 430.8 22.6 nmol MCA l 1 h 1 significantly higher than alkaline phosphatase 98.6 4.3 nmol MUF l 1 h 1 . The primary microbial colonizers of the overlaying water as determined by 16S rRNA gene sequence analysis were related to at least six different phylogenetic lineages of Bacilli and to Alphaproteobacteria Brevundimonas spp. and Caulobacter spp. . Large bacterial cells affiliated to one clade of Bacillus sp. were rare in the dried sediments, but constituted the majority of the planktonic microbial assemblage and of cells with detectable DNA synthesis until 28 h after re wetting. Their community contribution decreased in parallel with a rise of flagellated and ciliated protists. Estimates based on cell production rates suggested that the rapidlyenriched Bacillus sp. suffered disproportionally high loss rates from selective predation, thus favouring the establishment of a more heterogenic assemblage of microbes consisting of Proteobacteria, Actinobacteria and Cytophaga Flavobacteria . Our results suggest that the primary microbial colonizers of the water above dried sediments are passively released into the plankton and that their high growth potential is counteracted by the activity of bacterivorous protists. 10 Colonization Fazi_EM_08.pdf Articolo in rivista Blackwell Science. 1462 2912 Environmental microbiology Print Environmental microbiology Print Environ. microbiol. Print stefano.fazi FAZI STEFANO stefano.amalfitano AMALFITANO STEFANO alberto.puddu PUDDU ALBERTO annamaria.zoppini ZOPPINI ANNAMARIA TA.P02.002.003 Ruolo di comunita microbiche nella degradazione della sostanza organica e nella circolazione del carbonio nei sistemi acquatici